Gammadelta T cells: an alternative type of professional APC

γδ T cells as critical anti-tumor immune effectors

While the effector cells that mediate anti-tumor immunity have historically been attributed to αβ T cells and natural killer cells, γδ T cells are now being recognized as a complementary mechanism mediating tumor rejection. γδ T cells possess a host of functions ranging from antigen presentation to regulatory function and, importantly, have critical roles in eliciting anti-tumor responses where other immune effectors may be rendered ineffective. Recent discoveries have elucidated how these differing functions are mediated by γδ T cells with specific T cell receptors and spatial distribution. Their relative resistance to mechanisms of dysfunction like T cell exhaustion has spurred the development of therapeutic approaches exploiting γδ T cells, and an improved understanding of these cells should enable more effective immunotherapies.

The Spectrum of CAR Cellular Effectors: Modes of Action in Anti-Tumor Immunity

Chimeric antigen receptor-T cells have spearheaded the field of adoptive cell therapy and have shown remarkable results in treating hematological neoplasia. Because of the different biology of solid tumors compared to hematological tumors, response rates of CAR-T cells could not be transferred to solid entities yet. CAR engineering has added co-stimulatory domains, transgenic cytokines and switch receptors to improve performance and persistence in a hostile tumor microenvironment, but because of the inherent cell type limitations of CAR-T cells, including HLA incompatibility, toxicities (cytokine release syndrome, neurotoxicity) and high costs due to the logistically challenging preparation process for autologous cells, the use of alternative immune cells is gaining traction. NK cells and γδ T cells that do not need HLA compatibility or macrophages and dendritic cells with additional properties such as phagocytosis or antigen presentation are increasingly seen as cellular vehicles with potential for application. As these cells possess distinct properties, clinicians and researchers need a thorough understanding of their peculiarities and commonalities. This review will compare these different cell types and their specific modes of action seen upon CAR activation.

Immune Regulatory Networks and Therapy of γδ T Cells in Liver Cancer: Recent Trends and Advancements

The roles of γδ T cells in liver cancer, especially in the potential function of immunotherapy due to their direct cytotoxic effects on tumor cells and secretion of important cytokines and chemokines, have aroused research interest. This review briefly describes the basic characteristics of γδ T cells, focusing on their diverse effects on liver cancer. In particular, different subtypes of γδ T cells have diverse or even opposite effects on liver cancer. We provide a detailed description of the immune regulatory network of γδ T cells in liver cancer from two aspects: immune components and nonimmune components. The interactions between various components in this immune regulatory network are dynamic and pluralistic, ultimately determining the biological effects of γδ T cells in liver cancer. We also integrate the current knowledge of γδ T-cell immunotherapy for liver cancer treatment, emphasizing the potential of these cells in liver cancer immunotherapy.

Double-edged sword: γδ T cells in mucosal homeostasis and disease

The mucosa is a tissue that covers numerous body surfaces, including the respiratory tract, digestive tract, eye, and urogenital tract. Mucosa is in direct contact with pathogens, and γδ T cells perform various roles in the tissue. γδ T cells efficiently defend the mucosa from various pathogens, such as viruses, bacteria, and fungi. In addition, γδ T cells are necessary for the maintenance of homeostasis because they select specific organisms in the microbiota and perform immunoregulatory functions. Furthermore, γδ T cells directly facilitate pregnancy by producing growth factors. However, γδ T cells can also play detrimental roles in mucosal health by amplifying inflammation, thereby worsening allergic responses. Moreover, these cells can act as major players in autoimmune diseases. Despite their robust roles in the mucosa, the application of γδ T cells in clinical practice is lacking because of factors such as gaps between mice and human cells, insufficient knowledge of the target of γδ T cells, and the small population of γδ T cells. However, γδ T cells may be attractive targets for clinical use due to their effector functions and low risk of inducing graft-versus-host disease. Therefore, robust research on γδ T cells is required to understand the crucial features of these cells and apply these knowledges to clinical practices.

Exhausted intratumoral Vδ2- γδ T cells in human kidney cancer retain effector function

Gamma delta (γδ) T cells reside within human tissues including tumors, but their function in mediating antitumor responses to immune checkpoint inhibition is unknown. Here we show that kidney cancers are infiltrated by Vδ2- γδ T cells, with equivalent representation of Vδ1+ and Vδ1- cells, that are distinct from γδ T cells found in normal human tissues. These tumor-resident Vδ2- T cells can express the transcriptional program of exhausted αβ CD8+ T cells as well as canonical markers of terminal T-cell exhaustion including PD-1, TIGIT and TIM-3. Although Vδ2- γδ T cells have reduced IL-2 production, they retain expression of cytolytic effector molecules and co-stimulatory receptors such as 4-1BB. Exhausted Vδ2- γδ T cells are composed of three distinct populations that lack TCF7, are clonally expanded and express cytotoxic molecules and multiple Vδ2- T-cell receptors. Human tumor-derived Vδ2- γδ T cells maintain cytotoxic function and pro-inflammatory cytokine secretion in vitro. The transcriptional program of Vδ2- T cells in pretreatment tumor biopsies was used to predict subsequent clinical responses to PD-1 blockade in patients with cancer. Thus, Vδ2- γδ T cells within the tumor microenvironment can contribute to antitumor efficacy.

Engineering-Induced Pluripotent Stem Cells for Cancer Immunotherapy

Simple Summary

Induced pluripotent stem cells (iPSCs) that can be genetically engineered and differentiated into different types of immune cells, providing an unlimited resource for developing off-the-shelf cell therapies. Here, we present a comprehensive review that describes the current stages of iPSC-based cell therapies, including iPSC-derived T, nature killer (NK), invariant natural killer T (iNKT), gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs).

Abstract

Cell-based immunotherapy, such as chimeric antigen receptor (CAR) T cell therapy, has revolutionized the treatment of hematological malignancies, especially in patients who are refractory to other therapies. However, there are critical obstacles that hinder the widespread clinical applications of current autologous therapies, such as high cost, challenging large-scale manufacturing, and inaccessibility to the therapy for lymphopenia patients. Therefore, it is in great demand to generate the universal off-the-shelf cell products with significant scalability. Human induced pluripotent stem cells (iPSCs) provide an “unlimited supply” for cell therapy because of their unique self-renewal properties and the capacity to be genetically engineered. iPSCs can be differentiated into different immune cells, such as T cells, natural killer (NK) cells, invariant natural killer T (iNKT) cells, gamma delta T (γδ T), mucosal-associated invariant T (MAIT) cells, and macrophages (Mφs). In this review, we describe iPSC-based allogeneic cell therapy, the different culture methods of generating iPSC-derived immune cells (e.g., iPSC-T, iPSC-NK, iPSC-iNKT, iPSC-γδT, iPSC-MAIT and iPSC-Mφ), as well as the recent advances in iPSC-T and iPSC-NK cell therapies, particularly in combinations with CAR-engineering. We also discuss the current challenges and the future perspectives in this field towards the foreseeable applications of iPSC-based immune therapy.

Tumor resistance mechanisms and their consequences on γδ T cell activation

Human γδ T lymphocytes are predominated by two major subsets, defined by the variable domain of the δ chain. Both, Vδ1 and Vδ2 T cells infiltrate in tumors and have been implicated in cancer immunosurveillance. Since the localization and distribution of tumor-infiltrating γδ T cell subsets and their impact on survival of cancer patients are not completely defined, this review summarizes the current knowledge about this issue. Different intrinsic tumor resistance mechanisms and immunosuppressive molecules of immune cells in the tumor microenvironment have been reported to negatively influence functional properties of γδ T cell subsets. Here, we focus on selected tumor resistance mechanisms including overexpression of cyclooxygenase (COX)-2 and indolamine-2,3-dioxygenase (IDO)-1/2, regulation by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/TRAIL-R4 pathway and the release of galectins. These inhibitory mechanisms play important roles in the cross-talk of γδ T cell subsets and tumor cells, thereby influencing cytotoxicity or proliferation of γδ T cells and limiting a successful γδ T cell-based immunotherapy. Possible future directions of a combined therapy of adoptively transferred γδ T cells together with γδ-targeting bispecific T cell engagers and COX-2 or IDO-1/2 inhibitors or targeting sialoglycan-Siglec pathways will be discussed and considered as attractive therapeutic options to overcome the immunosuppressive tumor microenvironment.

Δ42PD1-TLR4 Augments γδ-T Cell Activation of the Transitional Memory Subset of CD4+ T Cells

TLR ligands can contribute to T cell immune responses by indirectly stimulating antigen presentation and cytokines and directly serving as co-stimulatory signals. We have previously reported that the human endogenous surface protein, Δ42PD1, is expressed primarily on (Vγ9)Vδ2 cells and can interact with TLR4. Since Vδ2 cells possess antigen presentation capacity, we sought to further characterize if the Δ42PD1-TLR4 interaction has a role in stimulating T cell responses. In this study, we found that stimulation of Vδ2 cells not only upregulated Δ42PD1 expression but also increased MHC class II molecules necessary for the antigen presentation. In a mixed leukocyte reaction assay, upregulation of Δ42PD1 on Vδ2 cells elevated subsequent T cell proliferation. Furthermore, the interaction between Δ42PD1-TLR4 augments Vδ2 cell stimulation of autologous CMV pp65-or TT-specific CD4⁺ T cell proliferation and IFN-γ responses, which was specifically and significantly reduced by blocking the Δ42PD1-TLR4 interaction. Furthermore, confocal microscopy analysis confirmed the interaction between Δ42PD1⁺HLA-DR⁺Vδ2 cells and TLR4⁺CD4 T cells. Interestingly, the subset of CD4⁺ T cells expressing TLR4 appears to be PD-1⁺ CD45RO⁺CD45RA⁺ transitional memory T cells and responded to Δ42PD1⁺HLA-DR⁺Vδ2 cells. Overall, this study demonstrated an important biological role of Δ42PD1 protein exhibited by Vδ2 antigen-presenting cells in augmenting T cell activation through TLR4, which may serve as an additional co-stimulatory signal.

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Δ42PD1 is co-expressed with MHC-II on activated Vδ2 cells

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Δ42PD1⁺MHC-II⁺Vδ2 cells interact directly with TLR4⁺CD4⁺T cells in 3D imaging

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TLR4 is highly expressed on the PD-1⁺CD45RO⁺CD45RA⁺CD4⁺T cell subset

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Δ42PD1-TLR4 selectively activates this subset of Ag-specific CD4⁺ T cells

Adjustments of γδ T Cells in the Lung of Schistosoma japonicum-Infected C56BL/6 Mice

Many kinds of lymphocytes are involved in Schistosoma japonicum (S. japonicum) infection-induced disease. γδ T cells comprise a small number of innate lymphocytes that quickly respond to foreign materials. In this study, the role of γδ T cells in the lung of S. japonicum-infected C56BL/6 mice was investigated. The results demonstrated that S. japonicum infection induces γδ T cell accumulation in the lung, expressing higher levels of CD25, MHCII, CD80, and PDL1, and lower levels of CD127 and CD62L (P < 0.05). The intracellular cytokines staining results illustrated higher percentages of IL-4-, IL-10-, IL-21-, and IL-6-producing γδ T cells and lower percentages of IFN-γ-expressing γδ T cells in the lung of infected mice (P < 0.05). Moreover, the granuloma size in lung tissue was significantly increased in Vδ^−/− mice (P < 0.05). In the lung of S. japonicum-infected Vδ^−/− mice, both type 1 and type 2 immune responses were decreased significantly (P < 0.05). In addition, the expression of CD80 and CD69 on B cells was decreased significantly (P < 0.05), and the SEA-specific antibody was markedly decreased (P < 0.05) in the blood of infected Vδ^−/− mice. In conclusion, this study indicates that γδ T cells could adjust the Th2 dominant immune response in the lung of S. japonicum-infected mice.

Suppressive activity of Vδ2+ γδ T cells on αβ T cells is licensed by TCR signaling and correlates with signal strength

Despite recent progress in the understanding of γδ T cells' roles and functions, their interaction with αβ T cells still remains to be elucidated. In this study, we sought to clarify what precisely endows peripheral Vδ2+ T cells with immunosuppressive function on autologous αβ T cells. We found that negatively freshly isolated Vδ2+ T cells do not exhibit suppressive behavior, even after stimulation with IL-12/IL-18/IL-15 or the sheer contact with butyrophilin-3A1-expressing tumor cell lines (U251 or SK-Mel-28). On the other hand, Vδ2+ T cells positively isolated through TCR crosslinking or after prolonged stimulation with isopentenyl pyrophosphate (IPP) mediate strong inhibitory effects on αβ T cell proliferation. Stimulation with IPP in the presence of IL-15 induces the most robust suppressive phenotype of Vδ2+ T cells. This indicates that Vδ2+ T cells' suppressive activity is dependent on a TCR signal and that the degree of suppression correlates with its strength. Vδ2+ T cell immunosuppression does not correlate with their Foxp3 expression but rather with their PD-L1 protein expression, evidenced by the massive reduction of suppressive activity when using a blocking antibody. In conclusion, pharmacologic stimulation of Vδ2+ T cells via the Vδ2 TCR for activation and expansion induces Vδ2+ T cells' potent killer activity while simultaneously licensing them to suppress αβ T cell responses. Taken together, the study is a further step to understand-in more detail-the suppressive activity of Vδ2+ γδ T cells.

Preservation of cytotoxic granule production in response to mycobacterial antigens by T-lymphocytes from vertically HIV-infected Brazilian youth on effective combined antiretroviral therapy

Background

HIV infection harms adaptive cellular immunity mechanisms. Long-term virological control by combined antiretroviral therapy (cART) reduces the risk of mycobacterial infections. Thus, we aimed to study cellular responses to mycobacterial antigens in 20 HIV-infected adolescents with at least one year of virological control (HIV-RNA <40 copies/mL) and 20 healthy adolescents.

Methods

We evaluated CD8 and γδ T-cell degranulation by measurement of CD107a membrane expression after stimulation with lysates from BCG (10 μg/mL) and H37RA Mycobacterium tuberculosis (Mtb, 10 μg/mL). Immune activation and antigen-presenting ability were also assessed by determination of HLA-DR, CD80, and CD86 markers.

Results

TCR γδ T-cell CD107a expression was similar between groups in response to mycobacterial antigens, and lower in the HIV-infected group in response to mitogen. Higher baseline HLA-DR expression and lower mycobacterial-stimulated expression was found within the HIV-infected group.

Conclusions

Similar degranulation in stimulated CD8+ and TCR γδ T-cells from HIV-infected adolescents, when compared to healthy controls suggests long-term immunological preservation with immune reconstitution under successful cART. However, differences in HLA-DR expression may represent ongoing inflammation and lower specific responses in HIV-infected youth. These features may be relevant in the context of the precocity and severity of vertically acquired HIV infection.

Antigen-Presenting Cell Characteristics of Human γδ T Lymphocytes in Chronic Myeloid Leukemia

Human γδ T lymphocytes play a role in the immune system defense against cancer. Their broad anti-cancer activity against different types of cancers makes them outstanding candidates for cancer immunotherapy. An issue of recent interest is whether their antigen presentation features are similar to mature dendritic cells. The antigen-presenting cell (APC)-like phenotype and function of γδ T lymphocytes have been confirmed in many clinical trials. In this study, to support the strong role played by Vγ9Vδ2 T cells against cancer, we provide evidence that Vγ9Vδ2 T cells activated with chronic myeloid leukemia (CML) cell lysate antigens can efficiently express an APC phenotype and function. Vγ9Vδ2 T cells derived from normal peripheral blood mononuclear cells were activated with tumor cell lysate, and the tumor-activated Vγ9Vδ2 T cells could recognize and kill CML through their cytotoxic activity. In conclusion, the Vγ9Vδ2 T cells activated by cancer cell lysate showed APC characteristics, and this may greatly increase interest in investigating their therapeutic potential in hematologic malignancies. Abbreviations: CML: chronic myeloid leukemia; APC: antigen-presenting cell; TCR: T cell receptor; MHC: major histocompatibility complex; N-BPs: nitrogen-containing bisphosphonates; IPP: isopentenyl pyrophosphate; PBMC: peripheral blood mononuclear cells; NKG2D: natural killer receptor group 2, member D; TRAIL: tumor necrosis factor-related apoptosis-inducing ligand.

New insights into mononuclear phagocyte biology from the visual system

Major advances in mononuclear phagocyte biology have been made but key questions pertinent to their roles in health and disease remain, including in the visual system. One problem concerns how dendritic cells can trigger immune responses from certain tightly regulated immune- privileged sites of the eye. Another, albeit separate, problem involves whether there are functional specializations for microglia versus monocytes in retinal neurodegeneration. In this Review, we examine novel insights in eye immune privilege and, separately, we discuss recent inroads concerning retinal degeneration. Both themes have been extensively studied in the visual system and show parallels with recent findings concerning mononuclear phagocytes in the central nervous system and in the periphery.

The effect of activated Mϕ1 on γδT cell-mediated killing of gastric cancer cells in vitro

A clear understanding of the interactions between classically activated macrophages (Mϕ1) and γδT cells may improve current therapeutic approaches, including that of immunotherapy for treating certain types of cancer. The present study aimed to expand the current knowledge by showing the effect of culture supernatants of Mϕ1 on the proliferation, cell surface marker expression and tumor suppression effects of γδT cells, and by exploring the potential mechanisms involved. In vitro, Mϕ1 were cultured by GM-CSF and IFN-γ. The isopentenyl pyrophosphate method was used to amplify human peripheral blood γδT cells. The surface markers of macrophages and γδT cells were detected by flow cytometry. The proliferation of γδT cells induced by the culture supernatants of Mϕ1 was investigated using the MTT assay. The lactate dehydrogenase method was used to detect the cytotoxicity of γδT cells on the SGC-7901 gastric cancer cell line. Ten days after cultivation, the percentage of γδT cells from the repertoire of naive cells, expanded from 4.21 to 91.27%. The percentage of cells expressing CD44 was 94%. The percentage of CD68 on cultured Mϕ1 was increased from 17.7 to 73.2%. The culture supernatants of Mϕ1 increased the proliferation of γδT cells compared with the control group (33.8% vs. 0, P<0.01). The culture supernatants of Mϕ1 increased the cytotoxicity of γδT cells compared with the control group (70.18 vs. 47.25%, P<0.01). In conclusion, the supernatant of cultured Mϕ1 promotes the proliferation of γδT cells and their cytotoxic effect on the SGC-7901 gastric cancer cell line.

Association of γδ T Cell Compartment Size to Disease Activity and Response to Therapy in SLE

OBJECTIVE

Although γδT cells are widely recognized as pivotal elements in immune-mediated diseases, their role in the pathogenesis of SLE and therapeutic outcome remains under explored. The current study aims to characterize the γδT cell compartment in SLE and correlate its status to disease severity and response to therapy.

METHODS

Human peripheral blood-derived γδ T cells were isolated from 14 healthy volunteers and 22 SLE patients (before and after 4 and 12 weeks following the onset of glucocorticoids (GC), mycophenolatemofetil (MMF) orhydroxychloroquine (HCQ) treatment). The γδ T cells were characterized using flow cytometry. In addition, serum concentration of IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10 and IL-17A was determined by cytometric bead array (CBA).

RESULTS

The SLEDAI scores dropped significantly following therapy in a subset of patients (responders-R) but not in some (non- responders-NR). Peripheral blood γδ T cells in general, and γ9+δ T cells and TNF-α/IL-17-secreting CD4-CD8-γδ T cell subsets in particular, were decreased in SLE compared to healthy controls. The numbers of the γδ T cell subsets reached levels similar to those of healthy controls following therapy in R but not in NR. Serum IL-6, IL-10 and IL-17 but not IFN-γ and TNF-α were significantly increased in SLE compared to the healthy controls and exhibited differential changes following therapy. In addition, inverse correlation was observed between SLEDAI scores and γδ T cell compartments, especially with TNF-α+γδT cells, TNF-α+γ9+δT cells and IL17+CD4-CD8-γδT cells subsets. Differential correlation patterns were also observed between serum cytokine levels and various γδ T cell compartments.

CONCLUSIONS

A strong association exists between γδ T cell compartments and SLE pathogenesis, disease severity and response to therapy.

CD4(+)B220(+)TCRγδ(+) T cells produce IL-17 in lupus-prone MRL/lpr mice

Systemic lupus erythematosus is an autoimmune disease with comprehensive immune cell disorders. Recent studies suggested that pro-inflammatory cytokine IL-17 plays important role in lupus, leaving the cellular sources and their pathogenic and physiologic characters largely unknown. In the current study, by using lupus-prone MRL/lpr mice, we demonstrated that Th17 response prevails in lupus disease regarding significantly accumulated serum IL-17, increased IL-17-producing splenocytes, and elevated phospho-STAT3 in CD4(+) T cells. Intracellular staining revealed that unusual CD4(+)B220(+) T cells are major IL-17-producing cells, whereas conventional CD4(+)B220(-) T cells are major IFN-γ-producing cells. Subsequent studies showed that CD4(+)B220(+) cells contains both αβ and γδ T cells in the spleen and thymus of MRL/lpr mice. Further study showed that around 60% of γδ T cells in MRL/lpr mice co-express both B220 and CD4 on their surface, and are the major RORγt(+) cells in MRL/lpr mice. Finally, CD4(+)B220(+) T cells alone do not proliferate, but could enhance the proliferation and IFN-γ-production of conventional CD4(+)B220(-) T cells. Our findings suggest the pathogenic role of unusual CD4(+)B220(+) T cells in lupus disease in MRL/lpr mice according to their IL-17-producing ability and stimulatory function for conventional CD4(+)B220(-) T cells.

Acute infection with bovine viral diarrhea virus of low or high virulence leads to depletion and redistribution of WC1(+) γδ T cells in lymphoid tissues of beef calves

The objective of this study was to determine the abundance and distribution of γδ T lymphocytes in lymphoid tissue during acute infection with high (HV) or low virulence (LV) non-cytopathic bovine viral diarrhea virus (BVDV) in beef calves. This study was performed using tissue samples from a previous experiment in which thirty beef calves were randomly assigned to 1 of 3 groups: LV [n=10; animals inoculated intranasally (IN) with LV BVDV-1a (strain SD-1)], HV [n=10; animals inoculated IN with HV BVDV-2 (strain 1373)], and control (n=10; animals inoculated with cell culture medium). On day 5 post inoculation, animals were euthanized, and samples from spleen and mesenteric lymph nodes (MLN) were collected to assess the abundance of WC1(+) γδ T cells. A higher proportion of calves challenged with BVDV showed signs of apoptosis and cytophagy in MLN and spleen samples compared to the control group. A significantly lower number of γδ T cells was observed in spleen and MLN from calves in HV and LV groups than in the control calves (P<0.05). In conclusion, acute infection with HV or LV BVDV resulted in depletion of WC1(+) γδ T cells in mucosal and systemic lymphoid tissues at five days after challenge in beef calves. This reduction in γδ T cells in the studied lymphoid tissues could be also due to lymphocyte trafficking to other tissues.

Vγ9Vδ2-T cells as antigen presenting cells for iNKT cell based cancer immunotherapy

CD1d-restricted invariant natural killer T cells (iNKT) constitute an important immunoregulatory T-cell subset involved in the induction of antitumor immune responses. Here, we provide a view on the recent observation that Vγ9Vδ2-T cells, through trogocytosis of CD1d-containing membrane fragments, have the capacity to act as antigen presenting cells for iNKT.

CD4 T-cells transduced with CD80 and 4-1BBL mRNA induce long-term CD8 T-cell responses resulting in potent antitumor effects

Therapeutic cancer vaccines are an attractive alternative to conventional therapies to treat malignant tumors, and more importantly, to prevent recurrence after primary therapy. However, the availability of professional antigen-presenting cells (APCs) has been restricted by difficulties encountered in obtaining sufficient professional APCs for clinical use. We have prepared an alternative cellular vaccine with CD4 T-cells that can be expanded easily to yield a pure and homogeneous population in vitro. To enhance their potency as a therapeutic vaccine, in vitro expanded CD4 T-cells were transfected with RNAs encoding the costimulatory ligands CD80, 4-1BBL, or both (CD80-T, 4-1BBL-T, and CD80/4-1BBL-T-cells, respectively). We observed augmented cell vitality in CD80/4-1BBL-T-cells in vitro and in vivo. Significant CD8 T-cell responses eliciting in vivo proliferation and cytotoxicity were obtained with CD80/4-1BBL-T-cell vaccination compared to CD80-T and 4-1BBL-T-cell vaccinations. In contrast, β2m-deficient CD80/4-1BBL-T-cells were not as effective as wile-type CD80/4-1BBL-T-cells in priming CD8 T-cells. Furthermore, CD80/4-1BBL-T-cell immunization resulted in curing established EG7 tumors, resulting in the generation of memory CD8 T-cell responses, and elicited therapeutic antitumor responses against B16 melanoma. These results suggest that CD4 T-cells endowed with costimulatory ligands allow the design of effective vaccination strategies against cancer.

Characteristics of γδ T cells in Schistosoma japonicum-infected mouse mesenteric lymph nodes

Gamma delta (γδ) T cells are mainly present in mucosa-associated lymphoid tissues, which play an important role in mucosal immunity. In this study, C57BL/6 mice were infected by Schistosoma japonicum and lymphocytes were isolated from the mesenteric lymph node (MLN) to identify changes in the phenotype and function of γδ T cells using flow cytometry. Our results indicated that the absolute number of γδ T cells from the MLNs of infected mice was significantly higher compared with normal mice (P < 0.05). In addition, the infected γδ T cells expressed a high level of the activated molecule CD69 (P < 0.01) and demonstrated an increasing population of CD4(+) γδ T cells (P < 0.05). MLN γδ T cells secrete interferon-γ (IFN-γ), interleukin (IL)-4, IL-9, and IL-17 in response to propylene glycol monomethyl acetate (PMA) plus ionomycin simulation, and the levels of IL-4, IL-9, and IL-17 increased significantly after S. japonicum infection (P < 0.05). Taken together, these findings indicated that S. japonicum infection could induce γδ T cell activation, proliferation, and differentiation in the MLN. Moreover, our results indicated that the expression of NKG2D (CD314) was not increased in γδ T cells after infection, suggesting that other mechanisms are involved in activating γδ T cells. Furthermore, higher expression of programmed death-1 (CD279) but not IL-10 was detected in the γδ T cells isolated from infected mice (P < 0.05), suggesting that the function of γδ T cells is inhibited gradually over the course of S. japonicum infection.

Changes in naïve and memory T-cells in elite swimmers during a winter training season

High intensity training regimens appear to put athletes at a higher risk of illness. As these have been linked to alterations in the proportions of differentiated T cells, how training load affects these populations could have important implications for athlete susceptibility to disease. This study examined the effect of a winter training season on the proportions of circulating naïve and memory T cells subsets of high competitive level swimmers. Blood samples were taken at rest at 4 time-points during the season: before the start of the season (t0-September), after 7weeks of an initial period of gradually increasing training load (t1-November), after 6weeks of an intense training cycle (t2-February) and 48h after the main competition (t3-April) and from eleven non-athlete controls at 2 similar time-points (t2 and t3). CD4, CD8 and gamma-delta (γδ) T cells expressing the naïve (CCR7(+)CD45RA(+)), central-memory (CM-CCR7(+)CD45RA(-)), effector-memory (EM-CCR7(-)CD45RA(-)) and terminal effector (TEMRA-CCR7(-)CD45RA(+)) were quantified by flow cytometry. Statistical analyses were performed using multilevel modeling regression. Both T CD4(+) naïve and CM presented a linear increase in response to the first moment of training exposure, and had an exponential decrease until the end of the training exposure. As for TCD4(+) EM, changes were observed from t2 until the end of the training season with an exponential trend, while TCD4(+) TEMRA increased linearly throughout the season. TCD8(+) naïve increased at t1 and decreased exponentially thereafter. TCD8(+) TEMRA values decreased at t1 and increased exponentially until t3. γδT-EM had an increase at t1 and an exponential decrease afterwards. In contrast, γδT-TEMRA decreased at t1 and exponentially increased during the remaining 20weeks of training. An increase in TEMRA and EM T cells alongside a decrease in naïve T cells could leave athletes more susceptible to illness in response to variation in training stimulus during the season.

Regeneration of stalled immune responses to transformed and infected cells using γδ T cells

Manipulation of the human immune system is becoming more of a therapeutic focus as a treatment option or complement. Prominent examples are the increasing use of monoclonal antibodies in combating malignant tumours, and the numerous adoptive immunotherapy trials underway. One important aspect of any use of the human immune system in this regard is to harness the power of professional antigen-presenting cells (pAPC), that is, dendritic cells (DC), to direct immune responses. Here, we review how recent findings regarding the biology of γδT cells have revealed that they, surprisingly, could serve as convenient tools for this purpose, in that they combine innate cytotoxic cell and pAPC functions in one cell type, with potential benefits in cancer immunotherapy and infectious disease.

CD1d-restricted antigen presentation by Vγ9Vδ2-T cells requires trogocytosis

CD1d-restricted invariant natural killer T cells (iNKT) constitute an important immunoregulatory T-cell subset that can be activated by the synthetic glycolipid α-galactosylceramide (α-GalCer) and play a dominant role in antitumor immunity. Clinical trials with α-GalCer-pulsed monocyte-derived dendritic cells (moDC) have shown anecdotal antitumor activity in advanced cancer. It was reported that phosphoantigen (pAg)-activated Vγ9Vδ2-T cells can acquire characteristics of professional antigen-presenting cells (APC). Considering the clinical immunotherapeutic applications, Vγ9Vδ2-T APC can offer important advantages over moDC, potentially constituting an attractive novel APC platform. Here, we demonstrate that Vγ9Vδ2-T APC can present antigens to iNKT. However, this does not result from de novo synthesis of CD1d by Vγ9Vδ2-T, but critically depends on trogocytosis of CD1d-containing membrane fragments from pAg-expressing cells. CD1d-expressing Vγ9Vδ2-T cells were able to activate iNKT in a CD1d-restricted and α-GalCer-dependent fashion. Although α-GalCer-loaded moDC outperformed Vγ9Vδ2-T APC on a per cell basis, Vγ9Vδ2-T APC possess unique features with respect to clinical immunotherapeutic application that make them an interesting platform for consideration in future clinical trials.

Mevalonate metabolism in cancer

Cancer cells are characterized by sustained proliferative signaling, insensitivity to growth suppressors and resistance to apoptosis as well as by replicative immortality, the capacity to induce angiogenesis and to perform invasive growth. Additional hallmarks of cancer cells include the reprogramming of energy metabolism as well as the ability to evade immune surveillance. The current review focuses on the metabolic reprogramming of cancer cells and on the immune system's capacity to detect such changes in cancer cell metabolism. Specifically, we focus on mevalonate metabolism, which is a target for drug and immune based cancer treatment.

Phenotype and regulation of immunosuppressive Vδ2-expressing γδ T cells

The proliferation and interleukin-2 production of CD4(+)CD25(-) αβ T cells were inhibited in a cell-contact manner by Vδ2 γδ T cells. The transcription factor Helios was constitutively expressed in about one-third of circulating γδ T cells and was upregulated by CD28-signaling. Our data suggest that Helios could serve as a marker for differential activation status rather than for regulatory T cells (Treg). Our findings also indicate that the interaction of CD86 on activated Vδ2 T cells and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on activated αβ T cells mediated the suppression because the suppressive effect was abolished by blocking the CD86:CTLA-4 interaction. Pre-treatment of Vδ2 T cells with Toll-like receptor 2 ligands enhanced phosphorylation of MAPKs, Akt, and NF-κB and partially abrogated the suppressive capacity, whereas on co-cultured responder T cells inhibitory molecules were downregulated and Akt and NF-κB phosphorylation was restored. Our results suggest that the regulation of αβ T cell proliferation by activated Vδ2 T cells might contribute to fine-tuning of αβ T cell responses.

Elevated apoptosis and impaired proliferation contribute to downregulated peripheral γ δ T cells in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the frequency of peripheral γ δ T cells in patients with systemic lupus erythematosus (SLE) and its correlation with disease activity and to analyze the apoptotic status, proliferation ability, and intracellular cytokine profile of these cells.

METHODS

Flow cytometry was performed to detect the percentage and intracellular cytokine expression of peripheral γ δ T cells from SLE patients. Annexin-V/PI double staining was applied to determine the proportion of apoptotic γ δ and CD3(+) T cells. γ δ T cell proliferation was analyzed by CFSE labeling technique.

RESULTS

The percentage and absolute number of γ δ T cells were remarkably decreased in active SLE patients compared to those in inactive patients and healthy controls, with γ δ T cell count negatively correlated with disease activity. Compared with healthy controls, peripheral γ δ T cells from active SLE patients exhibited higher apoptotic rate and lower proliferation ability, as well as elevated expression of intracellular IFN-γ , IL-4, IL-10, and TGF- β , but not IL-17 or Foxp3.

CONCLUSION

Decreased γ δ T cells in the peripheral blood of SLE patients might be caused by upregulated apoptosis and downregulated cell proliferation. These γ δ T cells may secret both pro- and anti-inflammatory cytokines to perform their functions in SLE.

Ovine skin-recirculating γδ T cells express IFN-γ and IL-17 and exit tissue independently of CCR7

γδ T cells continuously survey extralymphoid tissues, providing key effector functions during infection and inflammation. Despite their importance, the function and the molecules that drive migration of skin-recirculating γδ T cells are poorly described. Here we found that γδ T cells traveling in the skin-draining afferent lymph of sheep are effectors that produce IFN-γ or IL-17 and express high levels of the skin- and inflammation-seeking molecule E-selectin ligand. Consistent with a role for chemokine receptor CCR7 in mediating T cell exit from extralymphoid tissues, conventional CD4 and CD8T cells in skin-draining lymph were enriched in their expression of CCR7 compared to their skin-residing counterparts. In contrast, co-isolated γδ T cells in skin or lymph lacked expression of CCR7, indicating that they use alternative receptors for egress. Skin-draining γδ T cells were unresponsive to many cutaneous and inflammatory chemokines, including ligands for CCR2, CCR4, CCR5, CCR8, CCR10, and CXCR3, but showed selective chemotaxis toward the cutaneously expressed CCR6 ligand CCL20. Moreover, IL-17(+) γδ T cells were the most CCL20-responsive subset of γδ T cells. The data suggest that γδ T cells survey the skin and sites of inflammation and infection, entering via CCR6 and E-selectin ligand and leaving independent of the CCR7-CCL21 axis.

Plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with Plasmodium falciparum

BACKGROUND

Malaria is a major cause of morbidity and mortality worldwide with over one million deaths annually, particularly in children under five years. This study was the first to examine plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with Plasmodium falciparum from four semi-urban villages near Ile-Ife, Osun State, Nigeria.

METHODS

Blood was obtained from 231 children (aged 39-73 months) who were classified according to mean P. falciparum density per μl of blood (uninfected (n = 89), low density (<1,000, n = 51), medium density (1,000-10,000, n = 65) and high density (>10,000, n = 22)). IL-12p70, IL-10, Nitric oxide, IFN-γ, TNF, IL-17, IL-4 and TGF-β, C-C chemokine RANTES, MMP-8 and TIMP-1 were measured in plasma. Peripheral blood mononuclear cells were obtained and examined markers of innate immune cells (CD14, CD36, CD56, CD54, CD11c AND HLA-DR). T-cell sub-populations (CD4, CD3 and γδTCR) were intracellularly stained for IL-10, IFN-γ and TNF following polyclonal stimulation or stimulated with malaria parasites. Ascaris lumbricoides was endemic in these villages and all data were analysed taking into account the potential impact of bystander helminth infection. All data were analysed using SPSS 15 for windows and in all tests, p <0.05 was deemed significant.

RESULTS

The level of P. falciparum parasitaemia was positively associated with plasma IL-10 and negatively associated with IL-12p70. The percentage of monocytes was significantly decreased in malaria-infected individuals while malaria parasitaemia was positively associated with increasing percentages of CD54+, CD11c+ and CD56+ cell populations. No association was observed in cytokine expression in mitogen-activated T-cell populations between groups and no malaria specific immune responses were detected. Although A. lumbricoides is endemic in these villages, an analysis of the data showed no impact of this helminth infection on P. falciparum parasitaemia or on immune responses associated with P. falciparum infection.

CONCLUSIONS

These findings indicate that Nigerian children infected with P. falciparum exhibit immune responses associated with active malaria infection and these responses were positively associated with increased P. falciparum parasitaemia.

Comparative biology of γδ T cell function in humans, mice, and domestic animals

γδ T cells are a functionally heterogeneous population and contribute to many early immune responses. The majority of their activity is described in humans and mice, but the immune systems of all jawed vertebrates include the γδ T cell lineage. Although some aspects of γδ T cells vary between species, critical roles in early immune responses are often conserved. Common features of γδ T cells include innate receptor expression, antigen presentation, cytotoxicity, and cytokine production. Herein we compare studies describing these conserved γδ T cell functions and other, potentially unique, functions. γδ T cells are well documented for their potential immunotherapeutic properties; however, these proposed therapies are often focused on human diseases and the mouse models thereof. This review consolidates some of these studies with those in other animals to provide a consensus for the current understanding of γδ T cell function across species.

Nutritionally mediated programming of the developing immune system

A growing body of evidence highlights the importance of a mother's nutrition from preconception through lactation in programming the emerging organ systems and homeostatic pathways of her offspring. The developing immune system may be particularly vulnerable. Indeed, examples of nutrition-mediated immune programming can be found in the literature on intra-uterine growth retardation, maternal micronutrient deficiencies, and infant feeding. Current models of immune ontogeny depict a "layered" expansion of increasingly complex defenses, which may be permanently altered by maternal malnutrition. One programming mechanism involves activation of the maternal hypothalamic-pituitary-adrenal axis in response to nutritional stress. Fetal or neonatal exposure to elevated stress hormones is linked in animal studies to permanent changes in neuroendocrine-immune interactions, with diverse manifestations such as an attenuated inflammatory response or reduced resistance to tumor colonization. Maternal malnutrition may also have a direct influence, as evidenced by nutrient-driven epigenetic changes to developing T regulatory cells and subsequent risk of allergy or asthma. A 3rd programming pathway involves placental or breast milk transfer of maternal immune factors with immunomodulatory functions (e.g. cytokines). Maternal malnutrition can directly affect transfer mechanisms or influence the quality or quantity of transferred factors. The public health implications of nutrition-mediated immune programming are of particular importance in the developing world, where prevalent maternal undernutrition is coupled with persistent infectious challenges. However, early alterations to the immune system, resulting from either nutritional deficiencies or excesses, have broad relevance for immune-mediated diseases, such as asthma, and chronic inflammatory conditions like cardiovascular disease.

The Role of Plasmacytoid Dendritic Cells in Innate and Adaptive Immune Responses against Alpha Herpes Virus Infections

In 1999, two independent groups identified plasmacytoid dendritic cells (PDC) as major type I interferon- (IFN-) producing cells in the blood. Since then, evidence is accumulating that PDC are a multifunctional cell population effectively coordinating innate and adaptive immune responses. This paper focuses on the role of different immune cells and their interactions in the surveillance of alpha herpes virus infections, summarizes current knowledge on PDC surface receptors and their role in direct cell-cell contacts, and develops a risk factor model for the clinical implications of herpes simplex and varicella zoster virus reactivation. Data from studies involving knockout mice and cell-depletion experiments as well as human studies converge into a "spider web", in which the direct and indirect crosstalk between many cell populations tightly controls acute, latent, and recurrent alpha herpes virus infections. Notably, cells involved in innate immune regulations appear to shape adaptive immune responses more extensively than previously thought.

γδT cells in Juvenile Idiopathic Arthritis: Higher Percentages of Synovial Vδ1+ and Vγ9+ T Cell Subsets Are Associated with Milder Disease

Objective.

To analyze γδT cell subsets in peripheral blood (PB) and synovial fluid (SF) of patients with juvenile idiopathic arthritis (JIA), and to correlate γδT cell subsets with clinical characteristics.

Methods.

γδT cell subsets as percentages of CD3+ T cells in samples of PB (n = 25) and SF (n = 93) were analyzed by flow cytometry in 93 JIA patients. The percentage of Vγ9+ γδT cells after 10 days of in vitro expansion with either interleukin 2 (IL-2) or isopentenyl pyrophosphate (IPP) plus IL-2 was determined.

Results.

Both Vδ1+ and Vγ9+ γδT cell subsets were detected in SF of all patients, but only the percentage of Vδ1+ cells was higher in SF compared to PB (p < 0.01). The distribution of γδT cell subsets was similar in different JIA subgroups, whereas antinuclear antibody (ANA)-positive patients had a higher percentage of SF Vδ1+ T cells than ANA-negative patients (p < 0.01). The percentage of SF Vδ1+ T cells was inversely associated with age at onset, recurrence of synovitis, and erythrocyte sedimentation rate; and that of SF Vγ9+ T cells was inversely correlated with age at onset and was higher in patients who recovered from disease (n = 15). IPP-induced expansion of SF Vγ9+ T cells correlated with disease remission, whereas the expansion of SF Vγ9+ T cells in media with IL-2 alone was significantly greater in patients with uveitis.

Conclusion.

The percentage of Vδ1+ and Vγ9+ γδT cells among the SF T cells and their ability to respond to IPP or IL-2 correlated with specific outcomes of JIA, suggesting their role in the immunopathogenesis of this disease.

Bovine γδ T cells: cells with multiple functions and important roles in immunity

The γδ T-cell receptor (TCR)-positive lymphocytes are a major circulating lymphocyte population in cattle, especially in young calves. In contrast, human and mice have low levels of circulating γδ TCR(+) T cells (γδ T cells). The majority of the circulating γδ T cells in ruminants express the workshop cluster 1 (WC1) molecule and are of the phenotype WC1(+) CD2(-) CD4(-) CD8(-). WC1 is a 220000 molecular weight glycoprotein with homology to the scavenger receptor cysteine-rich (SRCR) family, closely related to CD163. The existence of 13 members in the bovine WC1 gene family has recently been demonstrated and although murine and human orthologues to WC1 genes exist, functional gene products have not been identified in species other than ruminants and pigs. Highly diverse TCRδ usage has been reported, with expanded variable genes in cattle compared to humans and mice. Differential γ chain usage is evident between populations of bovine γδ T cells, this may have implications for functionality. There is a growing body of evidence that WC1(+) γδ T cells are important in immune responses to mycobacteria and may have important roles in T cell regulation and antigen presentation. In this review, we will summarize recent observations in γδ T cell biology and the importance of γδ T cells in immune responses to mycobacterial infections in cattle.

Regulation by intestinal γδ T cells during establishment of food allergic sensitization in mice

BACKGROUND

Food allergy affects approximately 5% of children and is the leading cause of hospitalization for anaphylactic reactions in westernized countries. The mucosal adjuvant cholera toxin induces allergic sensitization to co-administered proteins in mice, while feeding the protein alone induces oral tolerance. Intestinal γδ T cells could be of importance in the induction of oral tolerance. This study aims to investigate whether γδ T cells have functional relevance in food allergic sensitization.

METHODS

Changes in γδ T cells on days 1, 2, 3, and 7 after initiation of food allergy were evaluated using flowcytometry. Furthermore, the anti-γδ T-cell receptor (TCR) antibody UC7 was used to block the γδ TCR in mice in vivo, followed by sensitization to peanut. After 4 weeks, peanut-specific antibodies in serum and cytokine production in spleen were measured.

RESULTS

Induction of food allergy resulted in a profound decrease in the percentage of γδ T cells in intestinal tissues and Peyer's Patches, but not in mesenteric lymph nodes or spleen. This decrease could be detected from days 1 to 2 after the initiation of food allergy and the number of γδ T cells returned to normal on day 7. Blockade of the γδ TCR resulted in elevated food allergic responses upon sensitization with peanut characterized by increased IgE and Th2 cytokine production in splenocytes.

CONCLUSION

These results demonstrate a unique regulatory role of γδ T cells, suggesting that targeting γδ T cells in the intestine may contribute to strategies to prevent and possibly treat food allergy.

γδ T-cell killing of primary follicular lymphoma cells is dramatically potentiated by GA101, a type II glycoengineered anti-CD20 monoclonal antibody

BACKGROUND

Anti-CD20 monoclonal antibodies are major therapeutic agents for patients with follicular lymphoma and work through complement-mediated cytotoxicity and antibody-dependent cellular cytotoxicity. Optimization of antibody-dependent cellular cytotoxicity, in particular by amplifying its effectors, could further increase the efficacy of anti-CD20 monoclonal antibodies.

DESIGN AND METHODS

We investigated the cytotoxic activity of Vγ9Vδ2 T cells against follicular lymphoma cells and whether this killing could be increased by promoting antibody-dependent cellular cytotoxicity with anti-CD20 monoclonal antibodies, in particular a type-II glycoengineered anti-CD20. Vγ9Vδ2 T cells were expanded in vitro in the presence of bromohydrin pyrophosphate (Phosphostim) and interleukin-2 and their ability to kill follicular lymphoma primary cells or cell lines was evaluated by flow cytometry cytotoxic T-lymphocyte assays in the presence or absence of three anti-CD20 monoclonal antibodies: the afucosylated GA101, the chimeric rituximab or the humanized ofatumumab. The ability of these cells to release perforin/granzyme and secrete interferon-γ when co-cultured with follicular lymphoma primary cells or cell lines in the presence or not of the three anti-CD20 monoclonal antibodies was also evaluated by CD107a staining and Elispot assays.

RESULTS

Phosphostim and interleukin-2 expanded Vγ9Vδ2 T cells were cytotoxic to primary follicular lymphoma cells and their cytotoxic potential was dramatically increased by GA101, a type II glycoengineered anti-CD20 monoclonal antibody, and to a lesser extent, by rituximab and ofatumumab. The increased cytotoxicity was associated with increased secretion of perforin/granzyme and interferon-γ.

CONCLUSIONS

In-vitro expanded Vγ9Vδ2 T cells efficiently kill primary follicular lymphoma cells and express CD16; anti-CD20 monoclonal antibodies, in particular GA101, dramatically increase the cytotoxic activity of expanded Vγ9Vδ2 T cells. These preclinical results prompt the development of clinical trials using this antibody dependent cellular cytotoxicity property of Vγ9Vδ2 T cells and anti-CD20 monoclonal antibodies.

Dendritic cells reveal a broad range of MHC class I epitopes for HIV-1 in persons with suppressed viral load on antiretroviral therapy

Background

HIV-1 remains sequestered during antiretroviral therapy (ART) and can resume high-level replication upon cessation of ART or development of drug resistance. Reactivity of memory CD8⁺ T lymphocytes to HIV-1 could potentially inhibit this residual viral replication, but is largely muted by ART in relation to suppression of viral antigen burden. Dendritic cells (DC) are important for MHC class I processing and presentation of peptide epitopes to memory CD8⁺ T cells, and could potentially be targeted to activate memory CD8⁺ T cells to a broad array of HIV-1 epitopes during ART.

Principal Findings

We show for the first time that HIV-1 peptide-loaded, CD40L-matured DC from HIV-1 infected persons on ART induce IFN gamma production by CD8⁺ T cells specific for a much broader range and magnitude of Gag and Nef epitopes than do peptides without DC. The DC also reveal novel, MHC class I restricted, Gag and Nef epitopes that are able to induce polyfunctional T cells producing various combinations of IFN gamma, interleukin 2, tumor necrosis factor alpha, macrophage inhibitory protein 1 beta and the cytotoxic de-granulation molecule CD107a.

Significance

There is an underlying, broad antigenic spectrum of anti-HIV-1, memory CD8⁺ T cell reactivity in persons on ART that is revealed by DC. This supports the use of DC-based immunotherapy for HIV-1 infection.

Effects of the culture supernatants of Mφ1 and Mφ2 on the killing activity of human γδT cells against gastric cancer SGC-7901 cells in vitro

AIM: To investigate the effects of the culture supernatants of classically activated macrophages (Mφ1) and alternatively activated macrophages (Mφ2) on the proliferation, cytotoxicity, and surface maker expression of gamma delta T (γδT) cells and explore potential mechanisms involved.

METHODS: Mφ1 were induced in vitro with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-γ (IFN-γ), while Mφ2 were induced with macrophage colony-stimulating factor (M-CSF). The isopentenyl pyrophosphate method was used to amplify human peripheral blood γδT cells. The surface markers on macrophages and γδT cells were determined by flow cytometry (FCM). Interleukin-10 (IL-10) and IL-12 levels in the culture supernatants of Mφ1 and Mφ2 were determined by enzyme-linked immunosorbant assay (ELISA) using commercial kits. The proliferation of γδT cells induced with the culture supernatants of Mφ1 and Mφ2 was investigated by methyl thiazoly tetrazolium (MTT) assay. The lactate dehydrogenase (LDH) method was used to detect the cytotoxicity of γδT cells against gastric cancer SGC-7901 cells.

RESULTS: After 10 days of induction culture, approximately 73.2% and 61.8% of Mφ1 and Mφ2 highly expressed CD68, respectively. The level of IL-12 secreted by Mφ1 was significantly higher than that secreted by Mφ2 (35 mg/L vs 9 mg/L, P < 0.001). The level of IL-10 secreted by Mφ1 was significantly lower than that secreted by Mφ2 (15 mg/L vs 87 mg/L, P < 0.001). The culture supernatant of Mφ1 could increase the proliferation of γδT cell when compared with those of Mφ2 and control cells (338% vs 11% and 0%, respectively; both P < 0.01). The positive rate of surface maker γδT cell receptor (γδTCR) on γδT cells induced with the culture supernatant of Mφ1 was higher than those on γδT cells induced with the culture supernatants of Mφ2 and control cells (97.3% vs 89.1% and 91.3%, respectively; both P < 0.05). The culture supernatant of Mφ1 could increase the cytotoxicity of γδT cells when compared with those of Mφ2 and control cells (70.18% vs 51.38% and 47.25%, respectively; both P < 0.01).

CONCLUSION: The culture supernatant of Mφ1 can increase the proliferation and cytotoxicity of γδT cells, whereas the culture supernatant of Mφ2 has no significant effects.

Cell-mediated immunity evaluation in foals infected with virulent equine herpesvirus-1 by multi-parameter flow cytometry

The cell-mediated immune (CMI) response of foals to virulent equine herpesvirus-1 (EHV-1) infection was evaluated by multi-parameter flow cytometry (FCM). Ten 7-8-month-old EHV-1 seronegative foals were infected intranasally with virulent EHV-1 and 10 foals served as uninfected controls. Blood samples were collected 6 and 7 weeks after infection to test for specific CMI responses to live heterologous EHV-1 recall antigen. The activation markers included major histocompatibility complex class II (MHC II), intracellular interferon gamma (IFN-gamma) and interleukin 4 (IL-4). The results from both tests were averaged before statistical analysis. Following EHV-1 stimulation, the MHC II expression index (EI) increased significantly in CD2+CD4+CD8- and CD2+CD4-CD8+ subsets of the infected group. At 4 days after incubation, the non-antigen stimulated CD2+CD4-CD8- subset of the infected group expressed a high percentage (61.1%) of MHC II. When stimulated with EHV-1, the MHC II expression declined significantly but remained at a relatively high percentage (34.4%). The IFN-gamma EI was significantly higher in infected foals in all major T cell subsets (CD2+) while only the CD2+CD4+CD8- subset showed a significant increase in intracellular IL-4 EI. The FCM results showed strong specific CMI responses to EHV-1 by all three tested parameters compared to the control group (p<0.01). The high MHC II expression in the CD2+CD4-CD8- subset suggests that this T cell subset may represent a gammadelta TCR repertoire and thereby plays an important role as antigen presenting cells in the horse, as reported in other species. Being able to simultaneously quantify the frequency of specific lymphocyte subsets and the expression of cytokines that characterize activation of lymphocytes and protective CMI by multi-parameter FCM enables evaluation of subset-specific CMI responses to EHV-1 infection. This system can be applied to measure CMI responses to other equine vaccines and pathogens.

Major role of gamma delta T cells in the generation of IL-17+ uveitogenic T cells

We show that in vitro activation of interphotoreceptor retinoid-binding protein (IRBP)-specific T cells from C57BL/6 mice immunized with an uveitogenic IRBP peptide (IRBP(1-20)) under TH17-polarizing conditions is associated with increased expansion of T cells expressing the gammadelta TCR. We also show that highly purified alphabeta or gammadelta T cells from C57BL/6 mice immunized with IRBP(1-20) produced only small amounts of IL-17 after exposure to the immunizing Ag in vitro, whereas a mixture of the same T cells produced greatly increased amounts of IL-17. IRBP-induced T cells from IRBP-immunized TCR-delta(-/-) mice on the C57BL/6 genetic background produced significantly lower amounts of IL-17 than did wild-type C57BL/6 mice and had significantly decreased experimental autoimmune uveitis-inducing ability. However, reconstitution of the TCR-delta(-/-) mice before immunization with a small number of gammadelta T cells from IRBP-immunized C57BL/6 mice restored the disease-inducing capability of their IRBP-specific T cells and greatly enhanced the generation of IL-17(+) T cells in the recipient mice. Our study suggests that gammadelta T cells are important in the generation and activation of IL-17-producing autoreactive T cells and play a major role in the pathogenesis of experimental autoimmune uveitis.

Reciprocal interactions between human mesenchymal stem cells and gammadelta T cells or invariant natural killer T cells

The immunomodulatory activities of human mesenchymal stem cells (MSCs) provide a rational basis for their application in the treatment of immune-mediated diseases, such as graft versus host disease and multiple sclerosis. The effects of MSCs on invariant natural killer T (iNKT) and gammadelta T cells, both involved in the pathogenesis of autoimmune diseases, are unknown. Here, we investigated the effects of MSCs on in vitro expansion of these unconventional T-cell populations. MSCs inhibited iNKT (Valpha24(+)Vbeta11(+)) and gammadelta T (Vdelta2(+)) cell expansion from peripheral blood mononuclear cells in both cell-to-cell contact and transwell systems. Such inhibition was partially counteracted by indomethacin, a prostaglandin E(2) inhibitor. Block of indoleamine 2,3-deoxygenase and transforming growth factor beta1 did not affect Valpha24(+)Vbeta11(+) and Vdelta2(+) cell expansion. MSCs inhibited interferon-gamma production by activated Valpha24(+)Vbeta11(+) and impaired CD3-mediated proliferation of activated Valpha24(+)Vbeta11(+) and Vdelta2(+) T cells, without affecting their cytotoxic potential. MSCs did not inhibit antigen processing/presentation by activated Vdelta2(+) T cells to CD4(+) T cells. In contrast, MSCs were lysed by activated Vdelta2(+) T cells through a T-cell receptor-dependent mechanism. These results are translationally relevant in view of the increasing interest in MSC-based therapy of autoimmune diseases.

Antigen specificity of gammadelta T cells depends primarily on the flanking sequences of CDR3delta

The structural basis that determines the specificity of gammadelta T cell receptor (TCR) recognition remains undefined. Our previous data show that the complementary determining region of human TCRdelta (CDR3delta) is critical to ligand binding. Here we used linear and configurational approaches to examine the roles of V, N-D-N, or J regions in CDR3delta-mediated antigen recognition. Surprisingly, we found that the binding activities of CDR3delta from different gammadelta TCRs to their target tissues and ligands depend on the conserved flanking sequences (V and J) but not as much on the D region of CDR3delta fragment. We further defined the key residues in the V and J regions of CDR3delta fragments, including the cysteine residue in the V fragment and the leucine residue in the J fragment that determine their ligand binding specificity. Our results demonstrate that TCRdelta primarily uses conserved flanking regions to bind ligands. This finding may provide an explanation for the limited number of gammadelta TCR ligands that have as yet been identified.

Immune manipulation of advanced breast cancer: an interpretative model of the relationship between immune system and tumor cell biology

This review summarizes some recent clinical immunological approaches with cytokines and/or antibodies for therapy of advanced breast cancer. It considers the recent advances in genetics and molecular tumor biology related to impaired immunosurveillance involving cytokines and growth factors to explain clinical results. Evasion of the host immune attack might be induced by the following groups of mechanisms: (a) tumor dependent (genomic instability, HLA class I antigen abnormalities, upregulation of fetal type nonclassical HLA class I molecules, epitope immunodominance, apoptosis inhibition by defective death receptor signaling, apoptosis of activated T cells, tumor cannibalism and constitutive activation of signal transducer, and activator of transcription-3 (Stat 3) and nuclear factor-kappaB (NF-kappaB) signaling); (b) host dependent (CD4+CD25+ regulatory T cells (T reg), CD4+ T cells anergy, Th2 antitumor immunity diversion and myeloid suppressor cells); (c) tumor and host dependent (lack of co-stimulation molecules, immunosuppressive cytokines (vascular endothelial growth factor (VEGF), interleukin (IL)-10, prostaglandin (PG)E2, transforming growth factor (TGF)-beta)). Cytokines and growth factors are involved in virtually all three types of mechanisms. These mechanisms are integrated with the current knowledge of tumor growth and inhibited apoptosis primarily mediated by cytokines and growth factors to propose an interpretation of the relationships among tumor cells, tumor stroma, and tumor-infiltrating lymphocytes. Tumor growth, defective immunorecognition and immunosuppression are the three principal effects considered responsible for immune evasion.

Clinical and immunological evaluation of zoledronate-activated Vgamma9gammadelta T-cell-based immunotherapy for patients with multiple myeloma

OBJECTIVE

To evaluate the potential anti-tumor activity of zoledronate-activated Vgamma9gammadelta T cells in vivo, we initiated a pilot study involving administration of zoledronate-activated Vgamma9gammadelta T lymphocyte-activated killer (LAK) cells to patients with multiple myeloma.

MATERIALS AND METHODS

Subjects (n = 6) received four intravenous infusions at 2-week intervals of zoledronate-activated Vgamma9gammadelta T LAK cells generated from the culture of peripheral blood mononuclear cells (PBMCs) in the presence of zoledronate and interleukin-2. If the M-protein level in the patient's serum remained at baseline following four intravenous infusions, the patient underwent four more treatments at 4-week intervals. Subjects (n = 6) received a median of 0.99 x 10(9) Vgamma9gammadelta T LAK cells per infusion.

RESULTS

No serious treatment-related adverse effects were observed during the study period. The percentage of Vgamma9gammadelta T cells in PBMCs and absolute numbers of Vgamma9gammadelta T cells in peripheral blood, particularly those of CD45RA(-)CD27(-) effector memory (TEM) Vgamma9gammadelta T-cell subsets increased in all the patients. Percentages of Vgamma9gammadelta T cells and TEM Vgamma9gammadelta T cells in bone marrow also increased in all the patients so far tested. M-protein levels in the serum remained at baseline in four of six patients and increased in two of six patients. Soluble major histocompatibility complex class I chain-related antigen A was detected only in the serum of patients whose M-protein level increased.

CONCLUSION

Administration of zoledronate-activated Vgamma9gammadelta T LAK cells is a safe and promising immunotherapy approach for treatment of patients with multiple myeloma.

Bovine natural killer cells

Natural killer (NK) cells have received much attention due to their cytotoxic abilities, often with a focus on their implications for cancer and transplantation. But despite their name, NK cells are also potent producers of cytokines like interferon-gamma. Recent discoveries of their interplay with dendritic cells and T-cells have shown that NK cells participate significantly in the onset and shaping of adaptive cellular immune responses, and increasingly these cells have become associated with protection from viral, bacterial and parasitic infections. Furthermore, they are substantially present in the placenta, apparently participating in the establishment of normal pregnancy. Consequently, NK cells have entered arenas of particular relevance in veterinary immunology. Limited data still exist on these cells in domestic animal species, much due to the lack of specific markers. However, bovine NK cells can be identified as NKp46 (CD335) expressing, CD3(-) lymphocytes. Recent studies have indicated a role for NK cells in important infectious diseases of cattle, and identified important bovine NK receptor families, including multiple KIRs and a single Ly49. In this review we will briefly summarize the current understanding of general NK cell biology, and then present the knowledge obtained thus far in the bovine species.

Mouse gammadelta T cells are capable of expressing MHC class II molecules, and of functioning as antigen-presenting cells

Although human and bovine gammadelta T cells were shown to express MHC class II antigen and function as APCs, attempts to determine if mouse gammabeta T cells have similar functions remained unsuccessful. We now show that gammadelta T cells derived from immunized mice also can be induced to express MHC class II and co-stimulatory molecules after activation in vitro, and are capable of antigen presentation. Using highly purified gammadelta T cells, we found that, unlike human gammadelta T cells, the expression of MHC class II molecules by mouse gammadelta T cells is limited to newly activated cells. Highest levels of MHC class II expression were seen on activated gammadelta T cells that had lost most surface-expressed gammadelta TCR while exhibiting increased levels of intracellular gammadelta TCR. In the absence of further stimulation, MHC class II expression gradually declined with the gammadelta T cells regaining their surface TCR. We also show that cytokine-activated gammadelta T cells can also express MHC class II antigen and exercise antigen-presenting activity.

Cross-presenting human gammadelta T cells induce robust CD8+ alphabeta T cell responses

Gammadelta T cells are implicated in host defense against microbes and tumors but their mode of function remains largely unresolved. Here, we have investigated the ability of activated human Vgamma9Vdelta2(+) T cells (termed gammadelta T-APCs) to cross-present microbial and tumor antigens to CD8(+) alphabeta T cells. Although this process is thought to be mediated best by DCs, adoptive transfer of ex vivo antigen-loaded, human DCs during immunotherapy of cancer patients has shown limited success. We report that gammadelta T-APCs take up and process soluble proteins and induce proliferation, target cell killing and cytokine production responses in antigen-experienced and naïve CD8(+) alphabeta T cells. Induction of APC functions in Vgamma9Vdelta2(+) T cells was accompanied by the up-regulation of costimulatory and MHC class I molecules. In contrast, the functional predominance of the immunoproteasome was a characteristic of gammadelta T cells irrespective of their state of activation. Gammadelta T-APCs were more efficient in antigen cross-presentation than monocyte-derived DCs, which is in contrast to the strong induction of CD4(+) alphabeta T cell responses by both types of APCs. Our study reveals unexpected properties of human gammadelta T-APCs in the induction of CD8(+) alphabeta T effector cells, and justifies their further exploration in immunotherapy research.